Theorem 2.3 [1]}
Let \(M\)  be an \(R\) –module and \(n\ge 0\)  an integer. Then there are exact sequences of functors:
\(0\rightarrow \mbox{Ext}\,^1_R(\mathcal {T}_{n+1}M,-)\rightarrow \mbox{Tor}\,_n^R(M,-)\rightarrow \mbox{Hom}\,_R(\mbox{Ext}\,^n_R(M,R),-)\rightarrow \mbox{Ext}\,^2_R(\mathcal {T}_{n+1}M,-),\) 
